/*-------------------------------------------------------------------------
 *
 * dir.c: directory operation utility.
 *
 * Portions Copyright (c) 2009-2013, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
 * Portions Copyright (c) 2015-2017, Postgres Professional
 *
 *-------------------------------------------------------------------------
 */

#include "pg_probackup.h"

#include <libgen.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <dirent.h>
#include <time.h>

#include "datapagemap.h"

/*
 * The contents of these directories are removed or recreated during server
 * start so they are not included in backups.  The directories themselves are
 * kept and included as empty to preserve access permissions.
 */
const char *pgdata_exclude_dir[] =
{
	PG_XLOG_DIR,
	/*
	 * Skip temporary statistics files. PG_STAT_TMP_DIR must be skipped even
	 * when stats_temp_directory is set because PGSS_TEXT_FILE is always created
	 * there.
	 */
	"pg_stat_tmp",
	"pgsql_tmp",

	/*
	 * It is generally not useful to backup the contents of this directory even
	 * if the intention is to restore to another master. See backup.sgml for a
	 * more detailed description.
	 */
	"pg_replslot",

	/* Contents removed on startup, see dsm_cleanup_for_mmap(). */
	"pg_dynshmem",

	/* Contents removed on startup, see AsyncShmemInit(). */
	"pg_notify",

	/*
	 * Old contents are loaded for possible debugging but are not required for
	 * normal operation, see OldSerXidInit().
	 */
	"pg_serial",

	/* Contents removed on startup, see DeleteAllExportedSnapshotFiles(). */
	"pg_snapshots",

	/* Contents zeroed on startup, see StartupSUBTRANS(). */
	"pg_subtrans",

	/* end of list */
	NULL,				/* pg_log will be set later */
	NULL
};

static char *pgdata_exclude_files[] =
{
	/* Skip auto conf temporary file. */
	"postgresql.auto.conf.tmp",

	/* Skip current log file temporary file */
	"current_logfiles.tmp",
	"recovery.conf",
	"postmaster.pid",
	"postmaster.opts",
	NULL
};

pgFile *pgFileNew(const char *path, bool omit_symlink);
static int BlackListCompare(const void *str1, const void *str2);

static void dir_list_file_internal(parray *files, const char *root,
								   bool exclude, bool omit_symlink,
								   bool add_root, parray *black_list);

/*
 * Create directory, also create parent directories if necessary.
 */
int
dir_create_dir(const char *dir, mode_t mode)
{
	char		copy[MAXPGPATH];
	char		parent[MAXPGPATH];

	strncpy(copy, dir, MAXPGPATH);
	strncpy(parent, dirname(copy), MAXPGPATH);

	/* Create parent first */
	if (access(parent, F_OK) == -1)
		dir_create_dir(parent, mode);

	/* Create directory */
	if (mkdir(dir, mode) == -1)
	{
		if (errno == EEXIST)	/* already exist */
			return 0;
		elog(ERROR, "cannot create directory \"%s\": %s", dir, strerror(errno));
	}

	return 0;
}

pgFile *
pgFileNew(const char *path, bool omit_symlink)
{
	struct stat		st;
	pgFile		   *file;

	/* stat the file */
	if ((omit_symlink ? stat(path, &st) : lstat(path, &st)) == -1)
	{
		/* file not found is not an error case */
		if (errno == ENOENT)
			return NULL;
		elog(ERROR, "cannot stat file \"%s\": %s", path,
			strerror(errno));
	}

	file = (pgFile *) pgut_malloc(sizeof(pgFile));

	file->mtime = st.st_mtime;
	file->size = st.st_size;
	file->read_size = 0;
	file->write_size = 0;
	file->mode = st.st_mode;
	file->crc = 0;
	file->is_datafile = false;
	file->linked = NULL;
	file->pagemap.bitmap = NULL;
	file->pagemap.bitmapsize = 0;
	file->ptrack_path = NULL;
	file->segno = 0;
	file->path = pgut_malloc(strlen(path) + 1);
	file->generation = -1;
	file->is_partial_copy = 0;
	strcpy(file->path, path);		/* enough buffer size guaranteed */

	return file;
}

/*
 * Delete file pointed by the pgFile.
 * If the pgFile points directory, the directory must be empty.
 */
void
pgFileDelete(pgFile *file)
{
	if (S_ISDIR(file->mode))
	{
		if (rmdir(file->path) == -1)
		{
			if (errno == ENOENT)
				return;
			else if (errno == ENOTDIR)	/* could be symbolic link */
				goto delete_file;

			elog(ERROR, "cannot remove directory \"%s\": %s",
				file->path, strerror(errno));
		}
		return;
	}

delete_file:
	if (remove(file->path) == -1)
	{
		if (errno == ENOENT)
			return;
		elog(ERROR, "cannot remove file \"%s\": %s", file->path,
			strerror(errno));
	}
}

pg_crc32
pgFileGetCRC(pgFile *file)
{
	FILE	   *fp;
	pg_crc32	crc = 0;
	char		buf[1024];
	size_t		len;
	int			errno_tmp;

	/* open file in binary read mode */
	fp = fopen(file->path, "r");
	if (fp == NULL)
		elog(ERROR, "cannot open file \"%s\": %s",
			file->path, strerror(errno));

	/* calc CRC of backup file */
	INIT_CRC32C(crc);
	while ((len = fread(buf, 1, sizeof(buf), fp)) == sizeof(buf))
	{
		if (interrupted)
			elog(ERROR, "interrupted during CRC calculation");
		COMP_CRC32C(crc, buf, len);
	}
	errno_tmp = errno;
	if (!feof(fp))
		elog(WARNING, "cannot read \"%s\": %s", file->path,
			strerror(errno_tmp));
	if (len > 0)
		COMP_CRC32C(crc, buf, len);
	FIN_CRC32C(crc);

	fclose(fp);

	return crc;
}

void
pgFileFree(void *file)
{
	if (file == NULL)
		return;
	free(((pgFile *)file)->linked);
	free(((pgFile *)file)->path);
	if (((pgFile *)file)->ptrack_path != NULL)
		free(((pgFile *)file)->ptrack_path);
	free(file);
}

/* Compare two pgFile with their path in ascending order of ASCII code. */
int
pgFileComparePath(const void *f1, const void *f2)
{
	pgFile *f1p = *(pgFile **)f1;
	pgFile *f2p = *(pgFile **)f2;

	return strcmp(f1p->path, f2p->path);
}

/* Compare two pgFile with their path in descending order of ASCII code. */
int
pgFileComparePathDesc(const void *f1, const void *f2)
{
	return -pgFileComparePath(f1, f2);
}

/* Compare two pgFile with their linked directory path. */
int
pgFileCompareLinked(const void *f1, const void *f2)
{
	pgFile	   *f1p = *(pgFile **)f1;
	pgFile	   *f2p = *(pgFile **)f2;

	return strcmp(f1p->linked, f2p->linked);
}

/* Compare two pgFile with their size */
int
pgFileCompareSize(const void *f1, const void *f2)
{
	pgFile *f1p = *(pgFile **)f1;
	pgFile *f2p = *(pgFile **)f2;

	if (f1p->size > f2p->size)
		return 1;
	else if (f1p->size < f2p->size)
		return -1;
	else
		return 0;
}

/* Compare two pgFile with their modify timestamp. */
int
pgFileCompareMtime(const void *f1, const void *f2)
{
	pgFile *f1p = *(pgFile **)f1;
	pgFile *f2p = *(pgFile **)f2;

	if (f1p->mtime > f2p->mtime)
		return 1;
	else if (f1p->mtime < f2p->mtime)
		return -1;
	else
		return 0;
}

/* Compare two pgFile with their modify timestamp in descending order. */
int
pgFileCompareMtimeDesc(const void *f1, const void *f2)
{
	return -pgFileCompareMtime(f1, f2);
}

static int
BlackListCompare(const void *str1, const void *str2)
{
	return strcmp(*(char **) str1, *(char **) str2);
}

/*
 * List files, symbolic links and directories in the directory "root" and add
 * pgFile objects to "files".  We add "root" to "files" if add_root is true.
 *
 * When omit_symlink is true, symbolic link is ignored and only file or
 * directory llnked to will be listed.
 */
void
dir_list_file(parray *files, const char *root, bool exclude, bool omit_symlink,
			  bool add_root)
{
	parray	   *black_list = NULL;
	char		path[MAXPGPATH];

	join_path_components(path, backup_path, PG_BLACK_LIST);
	/* List files with black list */
	if (root && pgdata && strcmp(root, pgdata) == 0 && fileExists(path))
	{
		FILE	   *black_list_file = NULL;
		char		buf[MAXPGPATH * 2];
		char		black_item[MAXPGPATH * 2];

		black_list = parray_new();
		black_list_file = fopen(path, "r");

		if (black_list_file == NULL)
			elog(ERROR, "cannot open black_list: %s", strerror(errno));

		while (fgets(buf, lengthof(buf), black_list_file) != NULL)
		{
			join_path_components(black_item, pgdata, buf);

			if (black_item[strlen(black_item) - 1] == '\n')
				black_item[strlen(black_item) - 1] = '\0';

			if (black_item[0] == '#' || black_item[0] == '\0')
				continue;

			parray_append(black_list, black_item);
		}

		fclose(black_list_file);
		parray_qsort(black_list, BlackListCompare);
	}

	dir_list_file_internal(files, root, exclude, omit_symlink, add_root,
						   black_list);
	parray_qsort(files, pgFileComparePath);
}

static void
dir_list_file_internal(parray *files, const char *root, bool exclude,
					   bool omit_symlink, bool add_root, parray *black_list)
{
	pgFile *file;

	file = pgFileNew(root, omit_symlink);
	if (file == NULL)
		return;

	/* skip if the file is in black_list defined by user */
	if (black_list && parray_bsearch(black_list, root, BlackListCompare))
	{
		/* found in black_list. skip this item */
		return;
	}

	if (add_root)
	{
		/* Skip files */
		if (!S_ISDIR(file->mode) && exclude)
		{
			char	    *file_name;
			int			i;

			/* Extract file name */
			file_name = strrchr(file->path, '/');
			if (file_name == NULL)
				file_name = file->path;
			else
				file_name++;

			/* Check if we need to exclude file by name */
			for (i = 0; pgdata_exclude_files[i]; i++)
				if (strcmp(file_name, pgdata_exclude_files[i]) == 0)
					/* Skip */
					return;
		}

		parray_append(files, file);
	}

	/* chase symbolic link chain and find regular file or directory */
	while (S_ISLNK(file->mode))
	{
		ssize_t	len;
		char	linked[MAXPGPATH];

		len = readlink(file->path, linked, sizeof(linked));
		if (len < 0)
			elog(ERROR, "cannot read link \"%s\": %s", file->path,
				strerror(errno));
		if (len >= sizeof(linked))
			elog(ERROR, "symbolic link \"%s\" target is too long\n",
				 file->path);

		linked[len] = '\0';
		file->linked = pgut_strdup(linked);

		/* make absolute path to read linked file */
		if (linked[0] != '/')
		{
			char	dname[MAXPGPATH];
			char	absolute[MAXPGPATH];

			strncpy(dname, file->path, lengthof(dname));
			join_path_components(absolute, dname, linked);
			file = pgFileNew(absolute, omit_symlink);
		}
		else
			file = pgFileNew(file->linked, omit_symlink);

		/* linked file is not found, stop following link chain */
		if (file == NULL)
			return;

		parray_append(files, file);
	}

	/*
	 * If the entry was a directory, add it to the list and add call this
	 * function recursivelly.
	 * If the directory name is in the exclude list, do not list the contents.
	 */
	while (S_ISDIR(file->mode))
	{
		bool			skip = false;
		DIR			    *dir;
		struct dirent   *dent;

		if (exclude)
		{
			int			i;
			char	    *dirname;

			/* skip entry which matches exclude list */
			dirname = strrchr(file->path, '/');
			if (dirname == NULL)
				dirname = file->path;
			else
				dirname++;

			/*
			 * If the item in the exclude list starts with '/', compare to the
			 * absolute path of the directory. Otherwise compare to the directory
			 * name portion.
			 */
			for (i = 0; exclude && pgdata_exclude_dir[i]; i++)
			{
				if (pgdata_exclude_dir[i][0] == '/')
				{
					if (strcmp(file->path, pgdata_exclude_dir[i]) == 0)
					{
						skip = true;
						break;
					}
				}
				else if (strcmp(dirname, pgdata_exclude_dir[i]) == 0)
				{
					skip = true;
					break;
				}
			}
			if (skip)
				break;
		}

		/* open directory and list contents */
		dir = opendir(file->path);
		if (dir == NULL)
		{
			if (errno == ENOENT)
			{
				/* maybe the direcotry was removed */
				return;
			}
			elog(ERROR, "cannot open directory \"%s\": %s",
				file->path, strerror(errno));
		}

		errno = 0;
		while ((dent = readdir(dir)))
		{
			char child[MAXPGPATH];

			/* skip entries point current dir or parent dir */
			if (strcmp(dent->d_name, ".") == 0 ||
				strcmp(dent->d_name, "..") == 0)
				continue;

			join_path_components(child, file->path, dent->d_name);
			dir_list_file_internal(files, child, exclude, omit_symlink, true, black_list);
		}
		if (errno && errno != ENOENT)
		{
			int errno_tmp = errno;
			closedir(dir);
			elog(ERROR, "cannot read directory \"%s\": %s",
				file->path, strerror(errno_tmp));
		}
		closedir(dir);

		break;	/* pseudo loop */
	}
}

/*
 * List data directories excluding directories from
 * pgdata_exclude_dir array.
 *
 * **is_root** is a little bit hack. We exclude only first level of directories
 * and on the first level we check all files and directories.
 */
void
list_data_directories(parray *files, const char *path, bool is_root,
					  bool exclude)
{
	DIR		   *dir;
	struct dirent *dent;
	int			prev_errno;
	bool		has_child_dirs = false;

	/* open directory and list contents */
	dir = opendir(path);
	if (dir == NULL)
		elog(ERROR, "cannot open directory \"%s\": %s", path, strerror(errno));

	errno = 0;
	while ((dent = readdir(dir)))
	{
		char		child[MAXPGPATH];
		bool		skip = false;
		struct stat	st;

		/* skip entries point current dir or parent dir */
		if (strcmp(dent->d_name, ".") == 0 ||
			strcmp(dent->d_name, "..") == 0)
			continue;

		join_path_components(child, path, dent->d_name);

		if (lstat(child, &st) == -1)
			elog(ERROR, "cannot stat file \"%s\": %s", child, strerror(errno));

		if (!S_ISDIR(st.st_mode))
			continue;

		/* Check for exclude for the first level of listing */
		if (is_root && exclude)
		{
			int			i;

			for (i = 0; pgdata_exclude_dir[i]; i++)
			{
				if (strcmp(dent->d_name, pgdata_exclude_dir[i]) == 0)
				{
					skip = true;
					break;
				}
			}
		}
		if (skip)
			continue;

		has_child_dirs = true;
		list_data_directories(files, child, false, exclude);
	}

	/* List only full and last directories */
	if (!is_root && !has_child_dirs)
	{
		pgFile	   *dir;

		dir = pgFileNew(path, false);
		parray_append(files, dir);
	}

	prev_errno = errno;
	closedir(dir);

	if (prev_errno && prev_errno != ENOENT)
		elog(ERROR, "cannot read directory \"%s\": %s",
			 path, strerror(prev_errno));
}

/*
 * Read names of symbolik names of tablespaces with links to directories from
 * tablespace_map or tablespace_map.txt.
 */
void
read_tablespace_map(parray *files, const char *backup_dir)
{
	FILE	   *fp;
	char		db_path[MAXPGPATH],
				map_path[MAXPGPATH];
	char		buf[MAXPGPATH * 2];

	join_path_components(db_path, backup_dir, DATABASE_DIR);
	join_path_components(map_path, db_path, "tablespace_map");

	/* Exit if database/tablespace_map don't exists */
	if (!fileExists(map_path))
	{
		elog(LOG, "there is no file tablespace_map");
		return;
	}

	fp = fopen(map_path, "rt");
	if (fp == NULL)
		elog(ERROR, "cannot open \"%s\": %s", map_path, strerror(errno));

	while (fgets(buf, lengthof(buf), fp))
	{
		char		link_name[MAXPGPATH],
					path[MAXPGPATH];
		pgFile	   *file;

		if (sscanf(buf, "%s %s", link_name, path) != 2)
			elog(ERROR, "invalid format found in \"%s\"", map_path);

		file = pgut_new(pgFile);
		memset(file, 0, sizeof(pgFile));

		file->path = pgut_malloc(strlen(link_name) + 1);
		strcpy(file->path, link_name);

		file->linked = pgut_malloc(strlen(path) + 1);
		strcpy(file->linked, path);

		parray_append(files, file);
	}

	fclose(fp);
}

/*
 * Print file list.
 */
void
print_file_list(FILE *out, const parray *files, const char *root)
{
	size_t		i;

	/* print each file in the list */
	for (i = 0; i < parray_num(files); i++)
	{
		pgFile	   *file = (pgFile *) parray_get(files, i);
		char	   *path = file->path;
		char		type;

		/* omit root directory portion */
		if (root && strstr(path, root) == path)
			path = JoinPathEnd(path, root);

		if (S_ISREG(file->mode) && file->is_datafile)
			type = 'F';
		else if (S_ISREG(file->mode) && !file->is_datafile)
			type = 'f';
		else if (S_ISDIR(file->mode))
			type = 'd';
		else if (S_ISLNK(file->mode))
			type = 'l';
		else
			type = '?';

		fprintf(out, "%s %c %lu %u 0%o", path, type,
				(unsigned long) file->write_size,
				file->crc, file->mode & (S_IRWXU | S_IRWXG | S_IRWXO));

		if (S_ISLNK(file->mode))
			fprintf(out, " %s", file->linked);
		else
		{
			char		timestamp[20];

			time2iso(timestamp, 20, file->mtime);
			fprintf(out, " %s", timestamp);
		}

		fprintf(out, " " UINT64_FORMAT " %d\n",
				file->generation, file->is_partial_copy);
	}
}

/*
 * Construct parray of pgFile from the file list.
 * If root is not NULL, path will be absolute path.
 */
parray *
dir_read_file_list(const char *root, const char *file_txt)
{
	FILE   *fp;
	parray *files;
	char	buf[MAXPGPATH * 2];

	fp = fopen(file_txt, "rt");
	if (fp == NULL)
		elog(errno == ENOENT ? ERROR : ERROR,
			"cannot open \"%s\": %s", file_txt, strerror(errno));

	files = parray_new();

	while (fgets(buf, lengthof(buf), fp))
	{
		char			path[MAXPGPATH];
		char			type;
		int				generation = -1;
		int				is_partial_copy = 0;
		unsigned long	write_size;
		pg_crc32		crc;
		unsigned int	mode;	/* bit length of mode_t depends on platforms */
		struct tm		tm;
		pgFile			*file;

		memset(&tm, 0, sizeof(tm));
		if (sscanf(buf, "%s %c %lu %u %o %d-%d-%d %d:%d:%d %d %d",
			path, &type, &write_size, &crc, &mode,
			&tm.tm_year, &tm.tm_mon, &tm.tm_mday,
			&tm.tm_hour, &tm.tm_min, &tm.tm_sec,
			&generation, &is_partial_copy) != 13)
		{
			/* Maybe the file_list we're trying to recovery is in old format */
			if (sscanf(buf, "%s %c %lu %u %o %d-%d-%d %d:%d:%d",
				path, &type, &write_size, &crc, &mode,
				&tm.tm_year, &tm.tm_mon, &tm.tm_mday,
				&tm.tm_hour, &tm.tm_min, &tm.tm_sec) != 11)
			{
				elog(ERROR, "invalid format found in \"%s\"",
					file_txt);
			}
		}

		if (type != 'f' && type != 'F' && type != 'd' && type != 'l')
		{
			elog(ERROR, "invalid type '%c' found in \"%s\"",
				type, file_txt);
		}
		tm.tm_isdst = -1;

		file = (pgFile *) pgut_malloc(sizeof(pgFile));
		file->path = pgut_malloc((root ? strlen(root) + 1 : 0) + strlen(path) + 1);
		file->ptrack_path = NULL;
		file->segno = 0;
		file->pagemap.bitmap = NULL;
		file->pagemap.bitmapsize = 0;

		tm.tm_year -= 1900;
		tm.tm_mon -= 1;
		file->mtime = mktime(&tm);
		file->mode = mode |
			((type == 'f' || type == 'F') ? S_IFREG :
			 type == 'd' ? S_IFDIR : type == 'l' ? S_IFLNK : 0);
		file->generation = generation;
		file->is_partial_copy = is_partial_copy;
		file->size = 0;
		file->read_size = 0;
		file->write_size = write_size;
		file->crc = crc;
		file->is_datafile = (type == 'F' ? true : false);
		file->linked = NULL;
		if (root)
			sprintf(file->path, "%s/%s", root, path);
		else
			strcpy(file->path, path);

		parray_append(files, file);

		if(file->is_datafile)
		{
			int find_dot;
			int check_digit;
			char *text_segno;
			size_t path_len = strlen(file->path);
			for(find_dot = path_len-1; file->path[find_dot] != '.' && find_dot >= 0; find_dot--);
			if (find_dot <= 0)
				continue;

			text_segno = file->path + find_dot + 1;
			for(check_digit=0; text_segno[check_digit] != '\0'; check_digit++)
				if (!isdigit(text_segno[check_digit]))
				{
					check_digit = -1;
					break;
				}

			if (check_digit == -1)
				continue;

			file->segno = (int) strtol(text_segno, NULL, 10);
		}
	}

	fclose(fp);

	/* file.txt is sorted, so this qsort is redundant */
	parray_qsort(files, pgFileComparePath);

	return files;
}

/*
 * Check if directory empty.
 */
bool
dir_is_empty(const char *path)
{
	DIR		   *dir;
	struct dirent *dir_ent;

	dir = opendir(path);
	if (dir == NULL)
	{
		/* Directory in path doesn't exist */
		if (errno == ENOENT)
			return true;
		elog(ERROR, "cannot open directory \"%s\": %s", path, strerror(errno));
	}

	errno = 0;
	while ((dir_ent = readdir(dir)))
	{
		/* Skip entries point current dir or parent dir */
		if (strcmp(dir_ent->d_name, ".") == 0 ||
			strcmp(dir_ent->d_name, "..") == 0)
			continue;

		/* Directory is not empty */
		closedir(dir);
		return false;
	}
	if (errno)
		elog(ERROR, "cannot read directory \"%s\": %s", path, strerror(errno));

	closedir(dir);

	return true;
}